Ballast construction



y 1950 A. E. FEINBERG 2,509,186

' BALLAST consmucnon Filed Sept. 1, 1948 a s 2i? 34 /30 I II v v Patented May 23, 1950 UNITED STATES PATENT waits.rin erae .1 ie i r vanc'e Transformer 00., Chicago, 111., a corporation of Illinois Application September 1, 1948. Serial No. 47,221"

eolaiiiis. (duals-142) This invention relates to a ballast construction for use in connection withv gaseous discharge devices known as fluorescent lamps and more particularly relates to the construction of the components used in the circuit for starting and maintaining the discharge of such lamps.

The primaryobject of the invention is to provide a construction in which the transformer as Well as the reactive inductances used in a circuit of the character to be described are all mounted as a single unit'and made up of-simple elements.

A further object of the invention is to provide atype of ballast construction operating a pair of fluorescent lamps in-a high power factor cirfruit in which a transformer, an inductive reacta-nce for providing a lagging current and a second inductive reactancefor providing a leading current are consecutively mounted together, res'ulting in considerable saving of iron and with a decrease in the temperature of theballast, but without in any way decreasing the efficiency thereof.

A further object of the invention is to provide a ballast construction of the character described in which components thereof will remain coolunder normal operating circumstances and especially in case one of the lamps is burned out.

The circuit in which my new device is intended to be employed is of the nature shown in'Patent 2,298,935 issued to a G. A. Freeman for Vapor lamp power factor correction. In Fig. 3 of this patent there is shown a construction in which there is provided a central coil, comprising an auto transformer, a. right hand coil connected in-series with a condenser inorder to provide a leading current,- and a, second coil on the left hand side of the transformer for providing a lagging current. Such an arrangement not only causes the lamps to light out of phase with one another, but also provides for power factor correction of the line so that while the device operates out of phase non-stroboscopically, the line efficiency is not impaired. p It has been found in the type of construction heretofore utilized that there is a tendency for the transformer coil to heatupduring operating conditions caused by short circuits of the lamps. It has'also been found that there is a critical spacing of the magnetic circuit gaps required in order to prevent excessive starting current.

My invention is based upon the discovery that if the lagging coil is interposed between the transformer and'the leading coil, then not only will the gap spacingbe less critical ,butas well the heat ing characteristics of the deviceduring operation 2 under both normal and abnormal conditions will be highly satisfactory. V V I w Further obj'ects will appear as the description of my novel ballastconstructionis set forthhereinafter, a preferred embodiment being illustrated and described for the purpose of aiding in the understanding and appreciation of the invention, it being understood that the features thereof are capable of broad variation, being limited only by the appended claims. w i p, p v

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures. of the drawings: 7 V V V Fig. 1 is a plain view of my ballastconstruction showing the arrangement of the windings. v

Fig. 2 is a schematic view showing the manner in which my ballast is connected into a circuit with two fluorescent lamps.

Referring now to the drawing, thereference character In designates generally the assembly of components comprising the ballast construction of my invention commonly known as brick. This assembly is made up of three components-- a transformer winding H, a choke coil or winding 12 for providing a lagging current to one of the fluorescent lamps and a second choke coil or winding [-3, for providing a leading current to the other of the pair of lamps. These components are arranged consecutively as shown in Fig. 1 of the drawing. The three components are mounted on an iron core structure formed of laminations in the conventional manner. v e

The transformer winding 1 I is mounted in the windows [4 and lji of a rectangular iron core it which is provided with npper horizontal portion IT, a lower horizontalportion i8, a central winding leg l9, a left vertical portion 20 anda right ve ic l p n 1-. as. wi be. d s d. the transformer; and its magnetic core will be positioned on the left end of the ballast assembly 10 as shown in Fig. 1. The core I8 of the transformer may be formed of lil laminations .inten leaved to provid'e the construction which gives rise to the windows i4 and It, although an E1 type of arrangement wouldalso be satisfactory. l m i iih t hfir l h 9 flux. Produced by the transformer winding II is confined to the horizontal portions [land lathe-vertical portions a d lan e e nce 9-.-.

m a ly .tqih right the t an o mer winding ll and its core Iii-,1 dispose the lagging coil winding l2, which is mounted on a stack 23 0 E laminations, providing the core for winding 12. The horizontal arms 24 and 26 as well as the central leg 26 have their free ends abutting against the right hand side of the core l8 adjacent the vertical member 2| thereof, being separated therefrom by a thin non-magnetic member 21, which forms a gap. It will be seen that the path for the flux generated by the lagging winding l2 consists of the horizontal arms 24 and 25, the vertical portion 29, the central leg 26 and the vertical portion 2| of the transformer winding core I6. the magnetic circuit of the winding l2 and thereby prevents saturation thereof.

The leading coil winding I3 is mounted on another stack 30 of E laminations having the horizontal portions 3| and 32 as well as the central leg 33 abutting against the vertical portion 29 of the stack 23, being separated therefrom by a thin, non-magnetic member 34, which forms a high reluctance magnetic gap similar to the gap 21. The magnetic circuit for the winding l3 consists of the horizontal portions 3| and 32, the vertical portion 35, the central leg 33 and the vertical portion 29 of the core 23. As in the case of the lagging winding and its core, the gap 3-4 prevents saturation of the magnetic circuit of the leading winding 33. It will be noted that the vertical leg 35 constitutes the extreme right end of the assembly of the three components.

The entire ballast may be retained in assembled condition by any well-known clamping means, diagrammatically indicated at 31.

In Fig. 2, I have illustrated the circuit with which my new ballast is intended to be used. The transformer winding II has its leads 4%] and 4| connected to a source of alternating current. The lead 40 is connected by means of the lead 42 to a pair of parallel fluorescent lamps 43 and 44 of conventional construction. The lamp 43 has a short-circuiting starter 34' connected in the usual manner and said lamp 43 is connected in series with the lagging winding I2 by means of the lead 41. The other end of the winding I2 is connected to the opposite end of the transformer winding I I through the lead 48.

The second lamp, 44, is connected in series with the lagging choke winding l3 by way of the lead 49 which has a condenser 58 therein so that the current of the lamp 44 leads to voltage of the line. Obviously, since the winding I2 is inductive the current in the tube 43 will lag the line voltage. It will be noted that the core 30 of the leading choke winding I3 is provided with a small winding which is connected in series with the starter 52 across the lamp 44. This is common practice and the winding 5| is known as a compensator winding. It provides additional starting current for the leading winding, since the distortion of the wave shape, lowering of the effective inductance of the leading choke winding due to the presence of condenser so serves to decrease the starting current in the lamp.

My invention is not limited to the specific type of construction utilizing a compensator winding as 5|, but is applicable as well as ballasts in which the winding 5| is not utilized.

Under normal circumstances with both lamps burning there is not much concern about the temperature of the ballast. If, however, one of the lamps should burn out, then the starter would constantly operate, causing a large fiow of current in the respective circuit in which the burnt out lamp is connected. This is most serious in the case of the lamp 44, since it causes heating of the coil 51 and the coil [3. Likewise, the temperature of the transformer II will also rise.

The gap 21 provides high reluctance in The result of my new arrangement with the lagging winding 12 and its iron core 23 interposed between the transformer II and the leading winding I3, is that the temperature does not readily rise, due to the existence of a large amount of iron between the two hot portions of the ballast.

I have constructed successful embodiments of my invention and by way of example, I have described hereinafter the structural details of my transformer. The overall dimensions of the transformer H were approximately 5% inches by 2% inches. The central winding leg IQ of the core [9 was approximately V8 inch wide and the horizontal portions H and I8 were approximately l e inch wide. The windows l4 and I5 of the core It were also %inch wide. The length of the core [6 Was one inch. The central winding legs 25 and 33 of the coil windings l2 and I3 respectively were each inch wide. The coil [2 was one inch in length and the coil [3 was 1%; inch in length. The gap 2! was .010 inch wide and the non-magnetic strip 34 was also .0l0 inch wide. The winding openings were all approximately 1 5 inches wide.

As for the windings, the transformer winding ll comprises 980 turns of number 2'? wire; the lagging secondary winding l 2 comprises 795 turns of number 26 wire; the leading secondary winding l3 comprised 945 turns of number 26 wire. The line 4| was tapped into the wiring of the primary winding l l at approximately the 420th turn thereof thereby producing an auto-transformer connection thereon. The usual and well-known insulating means, cannister, pitch, etc., were used in the assembly, along with a 3.5 microfarad condenser 50 rated at 330 volts and connected in series with the leading secondary l3.

The above described example gave excellent results, both as to cool operation as well as electrical performance.

I have found in the arrangement above described that many advantages accrue as a result of the construction. One of the features of my invention is that the spacing in the gaps 21 and 34 is not too critical. This means that for any adjusted operating current, variations in the thickness of the gap will not cause changes of any importance, thereby enabling rapid assembly of the ballast by unskilled workers and the use of gap material with ordinary commercial tolerances.

Another advantage which has been engendered by my invention is the decrease in the starting current for the lamp 43, which is the laugging lamp. The reason for this is attributed to the presence of considerably more iron in the vicinity of the lagging choke winding l2. If the lagging winding were on one side of the transformer as in previous constructions, the additional iron would not be present and under those circumstances the starting current is considerably higher than in my invention. This naturally increases the life of the ballast as well as the lamps.

Under normal operating conditions the lagging coil is the coolest of all three coils and hence its placement in the center increases the life of the components of the ballast. The leading windings I3 is higher in temperature than the lagging winding, due to the presence of the compensator 5|, which provides additional current during starting.

In addition to the advantages above described it should be obvious that my invention enables the ballast to be constructive of parts which are quite 53 common and easilyobtained and it is also obviions that. there is aconsiderable-saving of material aflfected.

It is believed that no further descriptionof my invention is necessary and it is desired to point out that although certain theories have been advanced as a basis for-the advantageous performance and features of my new ballast, I desire not to be limited to such theories; but would extend my invention to cover the construction described giving rise to the results set forth re gardless cf the manner in which this is accom-- plished,

What is claimed and described to secure by Letters Patent of the United States is:

l. A ballast constructionfora fluorescent lam-p circuit in which atransformer is connected with a source of alternating current and supplies each of a pair offluorescentlampswith power through inductive reactances, one of the reactances be ing provided with a series capacitance causing the phase of the current in the associatedlamp to lead the line voltage while the other reactance causes the phase of the current in its associated lamp to lag, said construction comprising said transformer and both of said inductive reactances being mounted on a laminated magnetic core structure with the lagging inductive reactance interposed between the transformer and the leading inductive reactance, said magnetic core structure consisting of a unitary assembly mounting said transformer and reactances, and clamping means holding same together.

2. A ballast construction for a fluorescent lamp circuit in which atransformer is connected with a source of alternating current and supplies each of a pair ofi'iuorescent lamps with power through inductive reactances, one of the reactances being provided with a series capacitance causing the phase of the current in the associated lamp to lead the line voltage while the other reactance causes the phase of the current in its associated lamp to lag, said. construction comprising said transformer and both of said inductive reactances being mounted on a laminated magnetic core structure with the lagging inductive reactance interposed between the transformer and the leading inductive reactance, said magnetic core structure" consisting of a unitary assembly mounting said transformer and reactances, and clamping means holding same together, and means comprising non-magnetic gaps arranged relative to the core structure to prevent saturation of said inductive reactances.

3. A ballast construction for a fluorescent lamp circuit in which a transformer is connected with a source of alternating current and supplies each of afpair of fluorescent lampsewith power through inductive reactances, one of "the reactances being provided with a series capacitance causing the phase of the current in the associated lamp to lead the line of voltage while the other reactance causes the phase of the current in its associated lamp to lag, said construction comprising said transformer and both of said inductive reactances being mounted on laminated magnetic core with the lagging indunctive reactance interposed between the transformer and the leading inductive reactance, said magnetic core structure consisting of a unitary assembly mounting said transformer and reactances, and clamping means holding same together, the magnetic core of said transformer being separated from the core of the lagging inducitve reactance by means of a non-magnetic gap whereby to confine its magnetic circuit to its core and providing a portion of the magneticcircuit of said lagging reactance on the side of said gap opposite to said lagginginductive reactance whereby the. magnetic circuit of said lagging inductive reactance is substantially insaturated during operation ofthe ballast.

4. A ballast construction for a fluorescent lamp circuit in which a transformer is connectedwith a source of alternating current and supplies each ofa pair of'fi'uoresc'ent lamps with power through inductive reactances, one of the reactances being provided with a series capacitance causing the phase of the cur-rent in the associated lamp to lead the line voltage while the other reactance causes the phase of thecurrent in its as-- sociated' lamp to lag, said construction comprising said transformer and both of said inductive reactances being mounted on laminated. mag netic cores with the lagging inductive reactance interposed between the transformer and the leading inductive reactance, said magnetic core structure consisting of a unitary assembly mounting said transformer and reactances, and clamping means holding same together, the magnetic coreof said transformer being separated from the core of the lagging'inductive reactance bymeans of a non-magneticgap whereby to confine its magnetic circuit to its core and providing a portion of the magnetic circuit of said lagging reactance on the side of said gap opposite to said industive reactance whereby the magnetic circuit of said lagging inductive reactance is substantially unsaturated during operation of the ballast, said leading inductive reactance being disposed adjacent-said lagging: inductive reactance on the side opposite tosaiditransformer and having its coreseparated from the core of said lagging inductive reactance by a non-magnetic gap, whereby the magnetic circuit of said lagging inductive reactance will not include a portion ofthe core of the leading inductive reacttance but the magnetic circuit of the leading inductive reactance will include aportion of the core of said lagging inductive reactance.

5.- A ballast construction for a fluorescent lamp circuit in which a transformer is connected with a source of alternating current and supplies each of a pair of fluorescent lamps with powersthrough inductive reactances, one of the reactances being provided with a series capacitance causing the phase of the currentin the associated lamp to lead the line voltage while the other reactance causes the phase of the current in its associated lamp to lag, said construction comprising said transformer and both of said inductive reactances being mounted on laminated magnetic cores with the lagging inductive reactance interposed between the transformer and the leading induc tive reactance, said magnetic core structure consisting of a unitary assembly mounting said transformer and reactances, and clamping means holding same together, the cores of the leading and lagging inductive reactance comprising open ended stacks of E laminations arranged alongside of the transformer core, the lagging core being separated from the transformer core by a non-magnetic gap and the leading core being separated from the lagging core by a non-magnetic gap, whereby the magnetic circuit of the lagging reactance will include a portion of the transformer core and the magnetic circuit of the leading reactance will include a portion of the core of the lagging reactance core.

6. A ballast construction for use with a pair of fluorescent lamps adapted to be operated out of phase one with the other in a circuit including a transformer, winding, pair of secondary windings in auto-transformer connection thereto, one of said secondary windings being provided with a series capacitance causing the phase of the current in the associated lamp to lead the line voltage while the other secondary causes the phase of the current in its associated lamp to lag, said windings comprising three stocks of laminations arranged side by side and fixed together and separated by non-magnetic high reluctance gaps, the lagging winding being mounted on the centrol stack and the transformer and leading windings being mounted on stacks on opposite sides of the lagging winding.

7. A ballast construction for use with a pair of fluorescent lamps adapted to be operated out of phase one with the other in a circuit including a transformer, winding, a pair of secondary windings in auto-transformer connection thereto, one of said secondary windings being provided with a series capacitance causing the phase of the current in the associated lamp to lead the line voltage while the other secondary causes the phase of the current in its associated lamp to lag, said windings comprising three stacks of laminations arranged side by side and fixed together and separated by non-magnetic high reluctance gaps, the lagging winding being mounted on the central stack and the transformer and leading windings being mounted on stacks on opposite sides of the lagging winding, the transformer stack including vertical magnetic paths on opposite sides of the winding and to one side of the gap between the transformer stack and the lagging winding stack, the lagging winding stack including only one vertical magnetic path alongside the winding opposite to the transformer stack, whereby the magnetic circuit of the lagging winding includes a portion of the transformer stack on the side opposite the gap from said lagging winding.

8. A ballast construction for use with a pair of fluorescent lamps adapted to be operated out of phase one with the other in a circuit including a transformer, winding, a pair of secondary windings in auto-transformer connection thereto, one of said secondary windings being provided with a series capacitance causing the phase of the current in the associated lamp to lead the line voltage while the other secondary causes the phase of the current in its associated lamp to lag, said windings comprising three stacks of laminations arranged side by side and fixed together and separated by non-magnetic high reluctance gaps, the lagging winding being mounted on the central stack and the transformer and leading windings being mounted on stacks on opposite sides of the lagging winding, the transformer stack including vertical magnetic paths on opposite sides of the winding and to one side of the gap between the transformer stack and the lagging winding stack, the lagging winding stack including only one vertical magnetic path alongside the winding opposite to the transformer stack, whereby the magnetic circuit of the lagging winding includes a portion of the transformer stack on the side opposite the gap from said lagging winding, the leading winding stack including only one vertical magnetic path alongside the winding opposite to the lagging winding stack, whereby the magnetic circuit of the leading winding includes a portion of the lagging winding stack on the side opposite the second gap from the leading winding.

9. A ballast construction for a fluorescent lamp circuit adapted to supply currents to a pair of fluorescent lamps and including a transformer winding and an inductive winding supply a lagging current to one lamp and a second inductive winding for supplying a leading current to the second lamp and adapted to be connected through a condenser thereto, a core structure for mounting the transformer Winding and both of the inductive windings together and consisting of a stack of laminations having the transformer Wound thereon and including vertical portions on opposite sides of the transformer winding, a stack of E laminations with the horizontal arms thereof abutting against one of the vertical portions of the transformer core and having a gap formed between said horizontal arms and said vertical portion, said lagging winding mounted on said stack of E laminations, and a second stack of E laminations having the horizontal legs thereof abutting against the vertical portion of the first stack of E laminations with a gap provided between said abutting legs and said vertical portion, the leading winding being mounted upon said second stack of E laminations, and means for maintaining all of said stacks in associated relationship.

ALBERT E. FEINBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,298,935 Freeman Oct. 13, 1942 2,317,344 Boucher & Kuhl (a) Apr. 27, 1943 2,346,621 Sola Apr. 11, 1944 2,351,914 Boucher & Kuhl (b) June 20, 1944 2,355,360 Boucher 8: Noble Aug. 8, 1944 2,382,638 Keiser et al Aug. 14, 1945 2,436,951 Bridges Mar. 2, 1948 2,465,103 Komm Mar. 22, 1949 

